1. Field of the Invention
The present invention relates to agricultural tillage implements or machines, and, more particularly, to hydraulic control systems of agricultural field cultivators.
2. Description of the Related Art
Farmers utilize a wide variety of agricultural implements or machines to prepare soil for planting, for the task of planting itself, for harvesting, and for other miscellaneous agricultural functions. Some such agricultural implements or machines may include two or more sections coupled together to perform multiple functions as they are pulled through fields by a tractor. For example, a field cultivator is capable of simultaneously tilling soil and leveling the tilled soil in preparation for planting. A field cultivator has a frame that carries a number of cultivator shanks with shovels at their lower ends for tilling the soil. The field cultivator converts compacted soil into a level seedbed with a consistent depth for providing excellent conditions for planting of a crop. Grass or residual crop material disposed on top of the soil is also worked into the seedbed so that it does not interfere with a seeding implement or machine subsequently passing through the seedbed. A field cultivator as described above may also include optional rear auxiliary implements for finishing the seedbed for seeding. For example, such rear auxiliary implements may include spike tooth harrows, spring tooth harrows, rolling (aka. crumbler) baskets, drag tines, etc., or any combination thereof.
As illustrated by the example of a field cultivator, agricultural tillage implements or machines have become increasingly multi-functional, complex, and physically larger machines. As a result, the hydraulic systems that are used to operate them, as well as to fold and unfold them for road transport, have also become increasingly complex. Often, these system include dozens of hydraulic cylinders, motors, valves, flow dividers, and other hydraulic devices. In order to function properly, such hydraulic systems must have any and all entrained air removed from them in a process commonly referred to as bleeding. Traditionally, this has involved simply opening or cycling valves in a certain order to allow the air to escape. However, with the increasingly complicated hydraulic systems used in agricultural implements or machines, often the traditional method of manually opening or cycling valves has become overly burdensome, time consuming, confusing, and unreliable. The problem of effectively bleeding air from the hydraulic systems of these agricultural implements or machines is further exacerbated by the fact that certain hydraulic circuits are not routinely used by the operated, such as bypasses and relief circuits.
What is needed in the art, therefore is a way to effectively, quickly, and efficiently bleed the hydraulic systems of agricultural implements or machines.